Method for washing laundry in a process-controlled household washing machine

ABSTRACT

The washing process W does not immediately begin with a heating phase t IK -t OS  at the beginning of a wash program with an untypically cold supply of water when a heating device is turned on, but rather once a delay phase D has elapsed. Said washing process ends after a post-wash phase without adding any heat energy once a defined constant time t EK -t OK  has elapsed after the delay phase. The temperature of the water or lye at the end of or after the end of the period during which water is added F is determined. If the determined temperature is less than a standard value S for the amount of water which has freshly run into the lye container prior to the beginning of the washing process W, the heating device is turned on and the beginning of the washing process is postponed according to a defined duration of time D.

The invention relates to a method for washing laundry in aprocess-controlled household washing machine comprising a wash liquidcontainer for receiving laundry and wash liquid intended for washing thelaundry, wherein or whereon a heating device and a temperature sensorare attached, wherein water for washing is poured into the wash liquidcontainer during a filling phase and the temperature sensor deliverssignals for the respective temperature of the water or the wash liquidto the process control system during the washing phase and said processcontrol system derives commands for controlling the heating device forheating the wash liquid from the temperature signals and wherein thewashing process runs with a heating phase which begins with switching onthe heating device and a post-wash phase at largely the sametemperature, and lasts for a defined constant time from the beginning ofswitching on the heating device until the end of the post-wash phase.

Washing machines of the type specified initially have been manufacturedfor many years by the proprietor of this patent and form a well-knownprior art. The background for defining the duration of the washingprocess by specifying it from the beginning of the heating phase and theend of the post-wash phase is to ensure uniformly good washing resultsas a result of the time factor of the so-called Sinnersch cycle whichprescribes a sum which is always the same for the factors temperature,time, mechanics and chemistry, remaining constant for the pure washingprocess.

Now, however, under extreme conditions the temperature of the intakewater is no longer within the postulated frame which assumes an inlettemperature of about 12° C. Fluctuations of ±3° are of little importancein this connection. Under extreme conditions, however, the predictedinlet temperature may specifically have deviated further downwards sothat inlet temperatures of, for example, 5° C. are possible. Thenhowever, the heating phase is extended so significantly that thesubsequent post-wash phase is too short because of the entire washingprocess being the same length. Then the mechanics factor has the samefraction but the temperature factor is reduced because the temperatureis too low over a large fraction of the washing process (in the heatingphase).

In order to remedy this and guarantee that the temperature factor alwayshas the same fractions, EP 0 859 304 B1 has proposed that the input ofthermal energy should be monitored and always kept the same underotherwise the same conditions.

At the same time, for washing household laundry the laundry in a washingmachine is washed in different program steps using a washing solution atvarying temperature. For this purpose, the laundry is inserted in alaundry drum rotatably mounted in a wash liquid container and thewashing solution (water with added cleansing agent) is supplied to thewash liquid container or the laundry drum. Different temperatures can beset in the washing program, usually ranging from tap water temperature(cold) up to 95° C. for a boil wash. The washing machine has a heatingdevice for heating the supplied water or the washing solution to the settemperature. Mechanical temperature sensors such as, for example, liquidexpansion sensors or bimetallic sensors or electronic temperaturesensors such as thermistors (NTC resistors) are arranged in the washingcontainer to regulate the temperature of the washing solution.

The known method for adjusting the temperature of the washing solutionin the washing process provides that, as usual, the temperature of thewashing solution is regulated between a maximum and a minimum value fora pre-defined regulating interval, during the regulation process the sumof the thermal energy supplied since the beginning of this regulatingprocess should be determined continuously and the supply of thermalenergy should be interrupted if the sum of the thermal energy suppliedexceeds a pre-determined process energy value. These measures however nolonger take into consideration the uniform duration of these regulatedwashing processes so that on the one hand the time factor can fluctuateand the rules of the Sinnersch cycle are no longer taken into account.This has the result that the cleaning effect is no longer uniformlygood. On the other hand, the customer can no longer reckon on a totalprocess duration of the same length for specific washing programs.

It is thus the object of the invention to ensure that in the processdescribed initially the influences of the temperature and time factorsinvolved should be guaranteed if the temperature of the intaken waterdeparts from the provided standard value.

According to the invention, this object is solved by the temperature ofthe water or the wash liquid being determined at or after the end of thefilling with water, that at a determined temperature of less than astandard value for the amount of water which has freshly run into thewash liquid container before the beginning of the washing process theheating device is switched on and that the beginning of the washingprocess is delayed by a defined time interval.

Since the beginning of the washing process, that is so that thebeginning of the guaranteed duration of the cleaning process for thelaundry can be specified automatically depending on the initialtemperature of the intaken water, the time duration for the cleaningprocess is determined independently of the initial temperature. It isthereby possible to adapt both the temperature factor, i.e. the quantityof input thermal energy and also the time factor to meet therequirements specified by the Sinnersch cycle. This also meansmaintaining the desired duration of washing processes under typicalhousehold conditions.

If according to an advantageous further development of the methodaccording to the invention, the temperature is first determined duringthe filling with water or wash liquid and before or during switching offthe heating device, the duration of the washing process can becalculated with the highest accuracy.

The standard value is best located in the range of 10° C. to 15° C.because the inlet temperature will regularly lie in this range. Underextreme conditions the inlet temperature can deviate substantiallydownwards, for example if the washing machine is located in a roomsubjected to large temperature fluctuations. After water having atemperature higher or lower than the standard value has been taken in,during the subsequent course of the filling process approximatelyuniformly temperature-controlled water (e.g. at 12° C.) is passedthrough the cold or warm piping system exposed in the room. However, thequantity of water which has run into the wash liquid container will havea mixing temperature which differs substantially (e.g. 12° C.) from thestandard value.

At the same time, upward deviations tend to be unharmful for maintainingthe cleaning effect even if as a result, the washing process is carriedout with an overall slightly higher input of thermal energy with aconstant effective washing time. Downward deviations will have noharmful effects as a result of postponing the beginning for the washingprocess because despite the washing solution beginning to act on thelaundry at lower temperature and the heating phase thereby beinglengthened, the duration of the effective washing process as a whole ismaintained.

According to an advantageous further development of the invention, thetime interval can be defined by reaching the standard value. If theinlet temperature should lie below the standard value, it is possible toprecisely set the beginning of the washing process by beginning theheating phase by switching on the heating device and waiting until thetemperature of the washing solution has reached the standard value (e.g.12° C.). The beginning of the washing process is only defined at thistime so that after a pre-determined time has elapsed from this time, thepost-wash phase is ended for example by pumping away the washingsolution or by adding further unheated water (cool down) to the washliquid container.

In another variant for an advantageous further development of theinvention, a pre-defined length is set for the duration of thepostponement of the beginning of the washing process. It can be assumedthat the deviations of the inlet temperature from the standard valuerarely have extreme values or fluctuate substantially and a standarddeviation is thus specified which is always assumed when the determinedinlet temperature deviates downwards by a pre-determined value from thestandard value. The value of this deviation can be 3° for example. Ifthis deviation is achieved or exceeded, a fixed pre-determined timeinterval is inserted for the postponement of the beginning of thewashing process. If the total input of thermal energy and time is thentoo great, the cleaning effect will at least not become inferior to thatdesired. On the other hand, a loss for those factors caused by atoo-short postponement if the actual inlet temperature should be lowerthan that corresponding to the pre-determined time interval for thedisplacement, is only very small and the resulting reduction in thecleaning effect would probably no longer be measurable.

The inventive method is explained hereinafter with reference to twodiagrams shown in the drawings. In the drawings

FIG. 1 shows a temperature profile of the washing solution as a functionof the time after a water intake with typical inlet temperature(standard value) and

FIG. 2 shows a temperature profile compared with that in FIG. 1 after awater intake with an inlet temperature below the standard value.

The temperature profile during washing programs in a washing machine istypically as shown in FIG. 1. At time 0 the washing program begins withan intake of unheated water, for example, from a domestic water supply.The incoming water has a temperature according to a standard value Sassumed for this example, namely 15° C. It is further assumed forsimplification purposes that the filling phase F is completed at timet_(0S). A water level sensor not described in further detail can now,for example, cause the closure of a switch in the circuit of the heatingdevice. As a result, the continuous heating of the washing solution (thewater which has flowed in has entrained washing agent from a flushingcontainer) begins until the target value for the set washing temperature(e.g. 60° C.) is reached. The heating device is then switched off againand the washing solution cools downs to a value below the targettemperature, e.g. 50° C., by the end of the washing process W which issubstantially characterised by the introduction of mechanics as a resultof rotations of the drum at intervals. The end of the washing process Wis determined by a fixed time interval t_(ES)-t_(0S) which is stored inthe washing program and a further supply of unheated water is initiatedat time t_(ES) whereby a cooling phase (so-called cool down) and therinsing phase R begins.

If the temperature of the inflowing water differs only slightly from thestandard value S=15° C., e.g. by only 3°, the washing process isoperated further according to the profile shown in the diagram inFIG. 1. This means that although the initial temperature is now slightlylower than typical, the washing process W now begins with a lowertemperature so that the heating phase t_(1S)-t_(0S) now takes a longertime than when beginning at 15° C., which time is now lost to part ofthe washing process W wherein the washing solution cools down againuntil the end t_(ES). This guarantees that the time factor is observed.However, the time interval within the washing process W in which thelaundry is washed with a temperature of the washing solution at least inthe vicinity of the target temperature is shortened compared with thetypical profile shown.

FIG. 2 shows an example wherein considerably cooler water (e.g. only 6°C. warm water) flows in at the beginning of a washing program. Forcomparison with the typical profile, the curve from FIG. 1 is alsoplotted as thin lines. Here the heating naturally also begins after theend of the filling phase F. Unlike in the typical profile however, thebeginning of heating does not coincide with the beginning of the washingphase W. Rather, a delay phase D is switched on here which, as in theexample shown, can either last until the temperature of the washingsolution being heated has reached the standard value S or has apre-determined duration which is approximately of similar length to theduration shown in the example.

At the end of the delay phase D, however, the washing process W beginsagain with a pre-determined time interval t_(EK)-t_(0K) which is thesame length as t_(ES)-t_(0S). This ensures that in any case of the inlettemperature in the washing process, the time factor cannot be too short.

1-5. (canceled)
 6. A method for washing laundry in a process-controlledhousehold washing machine comprising a wash liquid container forreceiving laundry and wash liquid intended for washing the laundry,wherein a heating device and a temperature sensor are attached, whereinwater for washing is poured into the wash liquid container during afilling phase and the temperature sensor delivers signals for therespective temperature of the water or the wash liquid to the processcontrol system during the washing phase and said process control systemderives commands for controlling the heating device for heating the washliquid from the temperature signals and wherein the typical washingprocess runs at a temperature of the water or the wash liquid at thelevel of a standard value with a heating phase which begins withswitching on the device and a post-wash phase without adding furtherheat energy, and lasts for a defined constant time from the beginning ofswitching on the heating device until the end of the post-wash phase,wherein: the temperature of the water or the wash liquid is determinedat or after the end of the filling with water; that at a determinedtemperature of less than a standard value for the amount of water whichhas freshly run into the wash liquid container before the beginning ofthe washing process the heating device is switched on; and that thebeginning of the washing process is delayed by a defined time interval(t_(OK)-t_(0S)) but from there on lasts the same time as the typicalwashing process.
 7. The method according to claim 6, wherein thetemperature is first determined during the filling with water or washliquid and before or during switching off the heating device.
 8. Themethod according to claim 6, wherein the standard value lies in therange of 10° C. to 15° C.
 9. The method according to claim 6, whereinthe time interval (t_(OK)-t_(0S)) is defined by reaching the standardvalue.
 10. The method according to claim 6, wherein the time interval(t_(OK)-t_(0S)) has a pre-defined length.
 11. A method for washinglaundry in a washing machine comprising a process control system forcontrolling operation of the washing machine, a wash liquid containerfor receiving laundry and water, a heating device for heating the waterwithin the wash liquid container, and a temperature sensor for detectingthe temperature of the water, the method comprising the acts of:providing wash liquid to the wash liquid container during a during afilling phase; detecting an initial temperature of the water with thetemperature sensor; activating the heating device to heat the waterduring a heating phase; performing a delay phase if the temperature ofthe water is below a pre-determined standard value, the delay phasecontinuing until the temperature of the water reaches the standardvalue; performing a washing phase and continuing the wash phase for apre-determined period of time; turning off the heating device when thetemperature of the water reaches a pre-determined washing temperature.12. The method according to claim 11, wherein the duration of thewashing phase has a pre-defined length.
 13. The method according toclaim 12, wherein the duration of the delay phase is variable inresponse to the period of time required for the temperature of the waterto reach the standard value.
 14. The method according to claim 11,wherein the standard value is between about 10° C. to 15° C.